You could disable RRDTool from running using this command in root SSH:
Code:
touch /etc/rrdtooldisable
This would disable the bandwidth stats generation from happening.
Now, I'm not certain I would agree with disabling it, since knowing how bandwidth is being used could help you if some user were exploited to see traffic patterns or if you were having one site being attacked for the bandwidth traffic patterns. It's actually helpful to have this information.
Next, with bandwidth reporting disabled, those users also will be unable to see their bandwidth data. If you are going to do that, you probably want to disable that option in Feature Manager as well:
WHM > Feature Manager > Edit a Feature List > Bandwidth Stats (uncheck)
Thanks!